Well, I think I broke it! I just don't know what...Help please!

I have a KM4 SR10, well, actually it's my sons. His is an older SR10 and I have a brand new one. Mine shoots .25's at ~355 fps and his was shooting them at ~300. I know that the previous owner of his rifle put a mad bull barrel on it and supposedly that can cause a lower FPS sometimes, but anyway.

I was attempting to up his FPS a bit so I purchased a new piston head because an airsoft tech at a local store suggested that, and then I had him throw a Wii Tech 120 spring in while he was at it.

I put the piston head in (which is a raptors airsoft brand) and the spring. Now when I try to fire in full-auto it only shoots about 3-8 rounds then locks up. It stops firing completely. When I switch it back to semi-auto it will fire like normal. But even when firing semi-auto sometimes it just kind of "siezes" up and won't fire. On top of all that, it still only shoots at about ~310fps with .25's. But around ~380fps with .20's. Very strange.

Does anyone have any ideas on what I may have broke? Before these changes the gun worked flawlessly aside from the lower FPS.

OH! Something else that happened when I first test fired after these changes was it started burning 20A fuses on my 15c lipos. Doesn't seem to do it on my 9.6v nimh

Interests:Keeping those damn squirrels from putting their filthy little paws on my peaches in my backyard. Oh, Yes. It's not just a hobby, its a passion!!

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Posted 26 July 2013 - 09:01 AM

Sorry for the late reply but you are burning through fuses because your gearbox is locking up. There can be numerous reasons why it's doing that since there are not much info to go on. Although I think that is may have something to do with your piston/piston head I would take it to a competent tech for repair or send it to KWA.